All units are TWh over the CONUS, except costs, which are either $ trillion or ¢/kWh-delivered-to-load. Bold indicates a total amount. Bold italics indicates a sum of totals. T&D, transmission and distribution.

↵a Transmission/distribution/maintenance losses are 5–10% of electricity generation for all generators except rooftop PV (1–2%) and solar thermal (2–4%). Transmission losses are averaged over short and long-distance (with high-voltage direct current) lines. Maintenance downtime is discussed in SI Appendix, Section S1.L. Storage efficiencies are given in SI Appendix, Table S1. Excess electricity is either stored or used to produce H2, so is not shed. Only excess heat is shed if heat storage is saturated.

↵c Each solar PV panel for rooftop and utility solar, installed in the climate model is a SunPower E20 435 W panel with panel area of 2.1621 m2, which gives a panel efficiency (Watts of power output per Watt of solar radiation incident on the panel) of 20.1%. The cell efficiency (power out per watt incident on each cell) is 22.5%. Each CSP plant before storage is assumed to have the characteristics of the Ivanpah solar plant, which has 646,457 m2 of mirrors and 2.17 km2 of land per 100 MW installed power and a CSP efficiency (fraction of incident solar radiation that is converted to electricity) of 15.796%, calculated as the product of the reflection efficiency of 55% and the steam plant efficiency of 28.72% (36).

↵d The capacity factor for hydropower from the simulation is 52.5%, which also equals that from ref. 22.

↵k Long-distance transmission costs are 1.2 (0.3–3.2) ¢/kWh for 1,200- to 2,000-km lines (37). The base case assumes that 30% of all wind and solar electric power generated are subject to long-distance transmission lines. This percent is varied in sensitivity tests in SI Appendix, Fig. S13.

↵l Storage costs are the product of the storage capacity and the capital cost per unit of storage capacity of each storage technology (SI Appendix, Table S1), summed over all technologies, annualized with the same discount rates and annual O&M percentages as for power generators, and divided by the annual-average load met in Table 2 (i.e., the total load met over 6 y divided by 6 y).

↵m H2 costs are 4.0 (1.96–6.05) ¢/kWh-to-H2 for the electrolyzer, compressor, storage equipment, and water. This cost equals 2.36 (1.16–3.57) $/kg-H2 divided by 59.01 kWh/kg-H2 required to electrolyze (53.37 kWh/kg-H2) and compress (5.64 kWh/kg-H2) H2 (38). These costs exclude electricity costs, which are included elsewhere in the table. The overall cost of H2 in ¢/all-kWh-delivered is equal to the cost in ¢/kWh-to-H2 multiplied by the fraction of delivered power used for hydrogen (11.46% = Table 1, column 6 divided by column 2).